1. Field of the Invention:
The present invention relates to a motorcycle and more particularly to a motorcycle having a fairing device designed for efficiently cooling an engine and associated components.
2. Description of the Relevant Art:
Known road-going sporting motorcycles have a fairing device covering the opposite sides of a front motorcycle area from a position in front of the instrument panel to the engine located between front and rear wheels for reducing air resistance and lift while running at high speed. One such a motorcycle is disclosed in Japanese Utility Model application No. 60-45284, for example.
The disclosed motorcycle has a radiator and an engine positioned between front and rear wheels, the radiator being located in front of the engine. The motorcycle also has a fuel tank disposed above the engine and a rider's seat or saddle positioned behind the fuel tank. The fairing device of the motorcycle comprises a front fairing covering the radiator and the engine, and a seat fairing or side cover covering an area behind the seat and opposite sides below the seat.
The motorcycle also includes an air passage duct disposed longitudinally in the motorcycle body. The air passage duct has an inlet port positioned in a space between the fuel tank and the engine closely to a rear portion of the radiator and is branched into two lateral members having outlet ports opening as nozzles on the opposite sides of the seat fairing positioned rearwardly of the legs of the rider.
Air flowing from behind the radiator is guided through the air passage duct and smoothly discharged therefrom on the opposite sides of the seat fairing without impinging upon the engine and related components. Therefore, air resistance arising from the air flow from behind the radiator is reduced. The seat fairing behind the seat is narrower than the rider, forming steps between itself and the seat. Air discharged from the outlet ports acts on and stabilizes ram air flowing along the fairing device. Therefore, air resistance can be lowered while keeping a preferred sheet fairing configuration.
Since, however, the air passage duct is accommodated in the fairing device or the motorcycle body, it is subject to space limitations imposed by other components. The air passage duct serves primarily to cool the radiator, and, for this purpose, has a flange-shaped guide disposed on the inlet port in covering relation to the entire rear surface of the radiator. Therefore, no sufficient ram air is supplied to the cylinder portion of the engine which is positioned behind or below the flange-shaped guide.
Japanese Laid-Open Patent Publication No. 60-67280, for example, discloses a motorcycle fairing device which does not have an air passage duct that would be subject to the aforesaid space limitations.
More specifically, the disclosed fairing device is mounted on a motorcycle having an engine positioned between front and rear wheels and having cylinders projecting upwardly from a crankcase and inclined forwardly, a frame having an engine hanger supporting the engine, and a radiator disposed in front of the engine. The fairing device includes a fairing that covers an area from a front frame portion to the opposite sides of the engine, a ram air inlet port defined in a front surface of the fairing, and outlet ports defined in respective side surfaces of the fairing, each of the outlet ports having a rear edge displaced inwardly of the front edge thereof in the transverse direction of the motorcycle.
It is desirable that after the radiator and the engine have been cooled by ram air, the ram air be immediately discharged out of the fairing device for increased engine cooling efficiency. However, inasmuch as the engine cylinder portion is positioned behind the outlet ports and no air passage duct or air guide for guiding ram air to the outlet ports is provided in the arrangement disclosed in Japanese Laid-Open Patent Publication No. 60-67280, the ram air that has cooled the engine cylinders cannot immediately be discharged out of the fairing but tends to remain in the fairing. As a result, the engine cooling efficiency cannot be increased. The tendency for cooling air to remain undischarged is greater with a full fairing or full cover type in which the fairing is joined to other motorcycle members such as side covers disposed above the rear wheel and on opposite sides beneath the rider's seat.